Echelon Mini FX - Manual (Page 33)

20 Introduction
Connections may be thought of as virtual wires. For example, the dimmer-switch device
in the dimmer-switch-light example could be replaced with an occupancy sensor, without
making any changes to the lighting device.
You can declare a maximum of 32 network variables in a Neuron C application to be
compiled with the Mini kit. The NodeBuilder FX Development Tool supports up to 254
network variables.
If you are creating a device to be used in a managed network, you typically don’t need
implement any code in the device application to handle the binding process, or the source
or destination devices for network variable values. If you are creating a device to be
used in a self-installed network, you need to implement code to support the enrollment
process, which is how you create network variable connections in such a network.
Neuron C provides an easy-to-use programming model familiar to any C language
programmer that encapsulates the complexity of distributed applications.
Configuration Properties
L ON W ORKS applications may also contain configuration properties. Configuration
properties allow the device’s behavior to be customized using a network management tool
such as the LonMaker tool or a customized plug-in created for the device (see the LNS
Plug-in Programmer’s Guide for more information on creating LNS device plug-ins).
For example, an application may allow an arithmetic function (add, subtract, multiply, or
divide) to be performed on two values received from two network variables. The function
to be performed could be determined by a configuration property. Another example of a
configuration property is a heartbeat interval setting that determines how often a device
transmits network variable updates over the network.
Like network variables, configuration properties have types that determine the type and
format of the data they contain.
You will need to declare the required configuration properties for your device’s Neuron C
application. The Mini kit supports configuration properties with an easy-to-use
programming model in Neuron C.
Functional Blocks
Applications in devices are divided into one or more functional blocks. A functional block
is a collection of network variables and configuration properties, which are used together
to perform one task. These network variables and configuration properties are called the
functional block members. For example, a digital input device could have four digital
input functional blocks that contain the configuration properties and output network
variable members for each of the four hardware digital inputs on the device. You will
need to declare the required functional blocks for your device’s Neuron C application. A
functional block is an implementation of a functional profile.
Functional Profiles
A functional profile defines mandatory and optional network variable and configuration
property members for a type of functional block. For example, the standard functional
profile for a light actuator has mandatory SNVT_switch input and output network
variables, optional SNVT_elapsed_tm and SNVT_elec_kwh output network variables,
and a number of optional configuration properties. Figure 1.6 illustrates the components
of the standard light actuator functional profile: